Integer::StringToInteger is accepting invalid(?) input

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Tim Offermann

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Jun 6, 2021, 3:38:29 PM6/6/21

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I was wondering if the current behavior of StringToInteger is perhaps a little bit too "friendly" - honestly I would have expected some exceptions on (IMHO) invalid input:

Dec from '011b' : 3.
Dec from '012b' : 1. !

Oct from '04711o' : 4711o
Oct from '04811o' : 411o !

Hex from '08Ah' : 8ah
Hex from '08A.' : 8h !
Hex from '08A' : 8h !!!

This is my code:

#include "integer.h"
#include <iostream>

int main(int argc, char *argv[])
{

std::cout << "Dec from '011b' : " << std::dec << CryptoPP::Integer("011b") << std::endl;

std::cout << "Dec from '012b' : " << std::dec << CryptoPP::Integer("012b") << " !" << std::endl;

std::cout << "\n";

std::cout << "Oct from '04711o' : " << std::oct << CryptoPP::Integer("04711o") << std::endl;

std::cout << "Oct from '04811o' : " << std::oct << CryptoPP::Integer("04811o") << " !" << std::endl;

std::cout << "\n";

std::cout << "Hex from '08Ah' : " << std::hex << CryptoPP::Integer("08Ah") << std::endl;

std::cout << "Hex from '08A.' : " << std::hex << CryptoPP::Integer("08A.") << " !" << std::endl;

std::cout << "Hex from '08A' : " << std::hex << CryptoPP::Integer("08A") << " !!!" << std::endl;

return 0;
}

It might be that the intention behind this originally was to accept additional characters like ":" or "-" in between for better readability (e.g. "31-65-30-63h" as "31653063h"). Out of my personal experience in the last days I would propose to limit this openess a little bit. Especially not allowing characters which are valid digits in one of the available notations might help prevent some (difficult to spot) usage error.